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/* Libiberty realpath. Like realpath, but more consistent behavior.
Based on gdb_realpath from GDB.
Copyright 2003 Free Software Foundation, Inc.
This file is part of the libiberty library.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street - Fifth Floor,
Boston, MA 02110-1301, USA. */
@deftypefn Replacement {const char*} lrealpath (const char *@var{name})
Given a pointer to a string containing a pathname, returns a canonical
version of the filename. Symlinks will be resolved, and ``.'' and ``..''
components will be simplified. The returned value will be allocated using
@code{malloc}, or @code{NULL} will be returned on a memory allocation error.
@end deftypefn
#include "config.h"
#include "ansidecl.h"
#include "libiberty.h"
#include <limits.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
/* On GNU libc systems the declaration is only visible with _GNU_SOURCE. */
extern char *canonicalize_file_name (const char *);
#if defined(HAVE_REALPATH)
# if defined (PATH_MAX)
# else
# if defined (MAXPATHLEN)
# endif
# endif
/* cygwin has realpath, so it won't get here. */
# if defined (_WIN32)
# define WIN32_LEAN_AND_MEAN
# include <windows.h> /* for GetFullPathName */
# endif
char *
lrealpath (const char *filename)
/* Method 1: The system has a compile time upper bound on a filename
path. Use that and realpath() to canonicalize the name. This is
the most common case. Note that, if there isn't a compile time
upper bound, you want to avoid realpath() at all costs. */
#if defined(REALPATH_LIMIT)
const char *rp = realpath (filename, buf);
if (rp == NULL)
rp = filename;
return strdup (rp);
#endif /* REALPATH_LIMIT */
/* Method 2: The host system (i.e., GNU) has the function
canonicalize_file_name() which malloc's a chunk of memory and
returns that, use that. */
char *rp = canonicalize_file_name (filename);
if (rp == NULL)
return strdup (filename);
return rp;
/* Method 3: Now we're getting desperate! The system doesn't have a
compile time buffer size and no alternative function. Query the
OS, using pathconf(), for the buffer limit. Care is needed
though, some systems do not limit PATH_MAX (return -1 for
pathconf()) making it impossible to pass a correctly sized buffer
to realpath() (it could always overflow). On those systems, we
skip this. */
#if defined (HAVE_REALPATH) && defined (HAVE_UNISTD_H)
/* Find out the max path size. */
long path_max = pathconf ("/", _PC_PATH_MAX);
if (path_max > 0)
/* PATH_MAX is bounded. */
char *buf, *rp, *ret;
buf = (char *) malloc (path_max);
if (buf == NULL)
return NULL;
rp = realpath (filename, buf);
ret = strdup (rp ? rp : filename);
free (buf);
return ret;
/* The MS Windows method. If we don't have realpath, we assume we
don't have symlinks and just canonicalize to a Windows absolute
path. GetFullPath converts ../ and ./ in relative paths to
absolute paths, filling in current drive if one is not given
or using the current directory of a specified drive (eg, "E:foo").
It also converts all forward slashes to back slashes. */
#if defined (_WIN32)
char buf[MAX_PATH];
char* basename;
DWORD len = GetFullPathName (filename, MAX_PATH, buf, &basename);
if (len == 0 || len > MAX_PATH - 1)
return strdup (filename);
/* The file system is case-preserving but case-insensitive,
Canonicalize to lowercase, using the codepage associated
with the process locale. */
CharLowerBuff (buf, len);
return strdup (buf);
/* This system is a lost cause, just duplicate the filename. */
return strdup (filename);